#pragma once
#include<iostream>
#include<vector>
#include<semaphore.h>
#include<pthread.h>

const static int defaultcap = 5;

template<class T>
class RingQueue{
private:
    void P(sem_t &sem)
    {
        sem_wait(&sem);
    }
    void V(sem_t &sem)
    {
        sem_post(&sem);
    }
    void Lock(pthread_mutex_t &mutex)
    {
        pthread_mutex_lock(&mutex);
    }

    void Unlock(pthread_mutex_t &mutex)
    {
        pthread_mutex_unlock(&mutex);
    }
public:
    RingQueue(int cap = defaultcap)
        :ringqueue_(cap), cap_(cap), c_step_(0), p_step_(0)
    {
        sem_init(&cdata_sem_, 0, 0);
        sem_init(&pspace_sem_, 0, cap);

        pthread_mutex_init(&c_mutex_, nullptr);
        pthread_mutex_init(&p_mutex_, nullptr);
    }

    void Push(const T& in) //生产
    {
        P(pspace_sem_);
        Lock(p_mutex_);
        ringqueue_[p_step_] = in;
        p_step_++; //位置后移，维持环形特性
        p_step_ %= cap_;
        Unlock(p_mutex_);

        V(cdata_sem_);
    }

    void Pop(T* out) //消费
    {
        P(cdata_sem_);

        Lock(c_mutex_);
        *out = ringqueue_[c_step_];
        c_step_++; //位置后移，维持环形特性
        c_step_ %= cap_;

        V(pspace_sem_);
    }

    ~RingQueue()
    {
        sem_destroy(&cdata_sem_);
        sem_destroy(&pspace_sem_);

        pthread_mutex_destroy(&c_mutex_);
        pthread_mutex_destroy(&p_mutex_);
    }
private:
    std::vector<T> ringqueue_;
    int cap_;

    int c_step_; //消费者下标
    int p_step_; //生成者下标

    sem_t cdata_sem_; //消费者关注的数据资源
    sem_t pspace_sem_; //生产者关注的空间资源

    pthread_mutex_t c_mutex_;
    pthread_mutex_t p_mutex_;
};